A converter in a steel-making plant for the refining of a steel melt generally is provided with means for blowing the melt within the converter with fresh gas, usually air, oxygen-enriched air or technical-purity oxygen, a converter stack by which the exhaust gases are withdrawn or removed from the converter and a washing system whereby the converter exhaust gases are scrubbed with water before being discharged.
In conventional systems of this general type, the sensible heat of the converter exhaust gas is recovered in a boiler (waste-heat boiler) which can be integrated with the converter stack. This sensible heat is thus recovered in the form of steam or hot water.
In certain cases, the converter stack can be provided with an after-burner device for recovering residual chemical energy of the converter exhaust gases. The heat generated in this fashion can be used to superheat the steam generated in the boiler. The efficiency of this type of energy recovery from converter exhaust gases is poor and leaves much to be desired.
Another disadvantage of conventional systems of the aforedescribed type for the recovery of energy from converter exhaust gases is that the converter operation is intermittent, i.e. the melt within the refining converter is only blown periodically. Thus energy can be recovered and utilized only in the cadence of the blowing. It has not been possible heretofore to recover energy continuously or independently from the blowing period of the converter period.
It has also been proposed in iron metallurgy to recover energy from exhaust gases under pressure in a turbine installation. For example, there is described in German published application (Auslegeschrift) DT-AS No. 24 39 758, a process of the latter type which is especially suitable for the recovery of energy from the exhaust gases of a high-pressure blast furnace. To our knowledge, this technique has not been applicable heretofore in the recovery of energy from converter exhaust gases.
Nor is it a simple matter to substitute a converter for a high-pressure blast furnace inasmuchas the gas output and operating conditions of the converter are vastly different from that of a blast furnace which, for all practical purposes, operates continuously.